This is/may be a wild guess: I too had 2x8Gb DDR3 1600 memory and saw some bizarre behavior, sometimes the bios would show 8G with 1 slot empty on a boot/reboot. I replaced with 2x4G DDR3 1333 MHz memory that i had sitting around and never saw this problem again. I have not had the time to go back and verify or find the root cause of the problem (run memtest etc).
I am beginning to have my doubts about how robustly NUC hardware designs have been tested, especially with the bizarre HDMI problems, not booting from thunderbolt, if you chain thunderbolt and a display, then its flakey as all hell. Come on Intel, show us your design chops ……
Thanks for the suggestion, if I get desperate I'll try 4x4 RAM instead, but the ability to have 16GB of RAM was one of the reasons for buying this model.
Does anybody else have 16GB of RAM and can install Windows 64bit? I'd be curious to see what I'm doing differently.
BTW, on the first unit I had I was able successfully install windows 7 64bit, but it started BSOD over and over. I tried to reinstall windows and got this issue. I RMAed the unit, and the new unit I can't install windows at all(hang at windows splash screen). Like I said ubuntu installs and runs just fine.
I just wanted to be a good forum user and post that I isolated my hang problems to the RAM as was suggested. I ran the ubuntu memtest86 and it found large blocks of errors in my original G.SKILL 2x8GB RAM. I replaced the RAM with CORSAIR VENGEANCE 2x8GB 1600MHz DDR3 ram and all the memtest86 tests pass now. Windows PE loads fine and many of the stability issues I was seeing disappeared.
I also switched the BIOS fan speed to "cool" just to be on the safe side. The NUC runs much cooler now and it is still essentially silent.